1. Field of the Invention
The present invention generally relates to ultrasonic imaging techniques, specifically medical diagnostic imaging techniques. In particular, the present invention relates to methods of ultrasonic detection of inflamed nerve roots and ultrasound apparatus used therefore.
2. Description of the Prior Art
Medical science has found it useful to sense the internal anatomy of the human body for various purposes such as detection of illness, observation of broken bones, monitoring of fetal viability, inspection of heart valve motion, and tumor detection.
External palpation is commonly used for locating and detecting easily sensed problems such as tumors, swollen organs, and ruptures. While external palpations are useful, they cannot be used to sense fine detail or to detect problems deep within the human body or those covered by other anatomical structures.
In the last 100 years or so, medical science has developed numerous other techniques of examining the internal structure of the body. Some techniques, such as nuclear particles methods and X-ray imaging including the CAT scan, tend to be expensive and require highly trained personnel. Additionally, these methods entail use of ionizing radiation which can damage human tissue.
Ultrasonic techniques have also been developed. These ultrasonic techniques are generally considered safe, can be implemented at low-cost, and can be designed to be easily used by personnel with little training. Examples of ultrasonic techniques include those described in U.S. Pat. No. 4,478,084 which describes an apparatus for ultrasound tomography and U.S Pat. No. 4,167,180 which describes a method and apparatus for performing an ultrasonic examination. However, the use of ultrasound as a diagnostic to study the spine is believed to be underdeveloped.
Some work has been done in ultrasonic spine scanning. Raghavendra and Epstein ("Sonography of the Spine and Spinal Cord," Radiologic Clinics of North America, Vol. 23, No. 1, March 1985 pp. 91-105) reported ultrasonic scanning of the spinal cord in young infants and those with spine defects such as spina bifida. However, no indication of detecting the spinal nerve root was given for persons with intact and developed spines. Also, Knake et al ("Neurosurgical Applications of Intraoperative Ultrasound," Radiologic Clinics of North America, Vol. 23, No. 1, March 1985 pp. 73-90) reported intraoperative techniques for ultrasonically scanning the spinal cord. However, no discussion of performing a similar function noninvasively was made.
Although the present inventor is unaware of any reported use of noninvasive ultrasound techniques to detect inflammation of nerve roots, it is believed that the ability to detect nerve root inflammation with ultrasound techniques would be a great advance over present method of palpation and heat detection. It will be appreciated that noninvasive ultrasonic detection of nerve root inflammation would be a great aid to health professionals in respect to detecting inflamed nerve roots so that the causes of the inflammation can be addressed before further injury.
One requirement of all ultrasonic imaging is a transducer to generate and detect the ultrasound waves. Because of simplicity of design, either a piezoelectric or an electromagnetic transducer is normally used. Examples of these transducers are the electromagnetic transducer described in U.S. Pat. No. 4,821,245 and the piezoelectric transducer probe described in U.S. Pat. No. 4,582,066.
As previously mentioned, one benefit of ultrasonic imaging is that it can be performed by personnel who do not necessarily have extensive training. This is especially true of machines designed for specific applications because the number of controls required to use the machine are often minimized. If the ultrasonic machine is not designed to suit a particular function, the large number of variables, including (1) velocity of sound wave propagation, (2) power input, (3) sound wave attenuation, (4) reflectiveness of various anatomical features, (5) wavelength, (6) receiver gain and (7) characteristics of the body being scanned, would require that the machine have so many controls that only highly trained technicians could use it.
It would, therefore, be useful and desirable to have both a noninvasive method of ultrasonically detecting inflamed nerve roots and ultrasound apparatus designed for use in accordance with such a method. It would be even more preferable if such a method could be implemented with suitable operating equipment which would enable operating personnel to detect inflamed nerve roots quickly and easily, without satisfying lengthy training requirements.